U.S. Patent Publication No. 2006/0229297 discloses (thio)-carbamoyl-cyclohexane derivatives that are D3 and D2 dopamine receptor subtype preferring ligands, having the formula (I):
(I)
wherein R1, R2, X, and n are as defined therein. One particular compound disclosed therein is trans-1{4-[2-[4-(2,3-dichlorophenyl)-piperazin-1-yl]-ethyl]-cyclohexyl}-3,3-dimethyl-urea, which is also known as trans-4-{2-[4-(2,3-dichlorophenyl)-piperazin-1-yl]-ethyl}-N,N-dimethylcarbamoyl-cyclohexylamine, the structural formula for which is shown below:

Compounds of formula (I) act as a dopamine receptor antagonists, particularly D3/D2 receptor antagonists, and are useful in the treatment and prevention of pathological conditions which require modulation of dopamine receptors.
In some cases, an appropriate salt of an active may improve certain properties suitable for pharmaceutical compounds (i.e., stability, handling properties, ease of large scale synthesis, etc.). However, selection of a suitable salt for a particular active agent is not always straightforward, since the properties of salts of different compounds formed with the same salt forming agent may differ greatly. Moreover, formation of particular salts of a compound possessing more than one basic centre may be difficult to achieve in high yield due to formation of multiple products.